Magnetic junk basket



July 14, 1970 H. T. EHRLICH MAGNETIC JUNK BASKET Filed June 27, 1968 Hlw 6 a n ZVM/ 1N VENTOR- United States Patent O 3,520,359 MAGNETIC JUNK BASKET Herman T. Ehrlich, 2001 Patton Road, Great Bend, Kans. 67530 Filed June 27, 1968, Ser. No. 740,668 Int. Cl. E21b 31 06 U.S. Cl. 166-65 8 Claims ABSTRACT F THE DISCLOSURE A well tool for retrieving magnetic objects from a well and adapted for connection to a pipe string. The body of the tool is provided with a centrally disposed longitudinally extending circulation fluid bore concentric with the bore of the pipe string. A plurality of permanent magnets, carried in a non-magnetic cage are secured within the body of the tool by a pole plate secured to the body by welding. The cage is also protected from dislodgement from the body by the pressure of the circulation fluid by means of a circulation bore sleeve which prevents the circulation fluid from acting against the top of the cage.

The present invention relates to a magnetic tool for retrieving magnetic objects and fragments from a Well bore. More particularly, the present invention relates to a magnetic well tool provided with a plurality of permanent magnets and constructed so as to substantially preclude dislodgement or loss of any of the components of the tool during utilization thereof.

Numerous magnetic well tools have been proposed heretofore. However, such tools are generally characterized by inherent constructional or operational deficiencies which render the tools highly unsuitable for the recovery of magnetic objects, i.e. pipes, bits, bit cones, hammers, etc. which gather at the bottom of a borehole as a result of tool failures or are accidentally dropped down the borehole. The most prevalent deficiencies of magnetic well tools proposed heretofore relate to the tendency for portions of the tool to actually become dislodged during utilization of the tool thereby further adding to the junk that must be retrieved from the borehole. In addition, magnetic retrieving tools provided heretofore do not include satisfactory means for the directing of circulation fluid to effect dislodgement of shale, sand or other caveins of non-magnetic nature so as to permit the magnetic means of the tool to come into magnetic contact with the junk to be retrieved.

It is therefore an object of the present invention to provide a magnetic well tool constructed so as to substantially preclude the dislodgement of components of the tool during utilization thereof.

Another object of the present invention is to provide a magnetic well tool having improved circulation fluid directing mean-s.

A further object of the present invention is to provide an improved construction for a magnetic well tool wherein means are provided for substantially precluding the dislodgement of the magnetic means of the tool by circulation fluid passing downwardly through the tool from the circulation fluid bore of a drill pipe string with which the tool is associated during utilization thereof.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. l shows a tool embodying the present invention carried on the lower end of a pipe string;

Patented July 14, 1970 FIG. 2 is an enlarged bottom elevational view of the tool of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the tool of FIG. 1 taken substantially along the plane of the line 3--3 of FIG. 2; and

FIG. 4 is a transverse cross-sectional view of the tool of FIG. l taken substantially along the plane of the line 4-4 of FIG. 3.

Referring now to the drawings in greater detail and FIG. 1 in particular, the numeral 10 designates an exemplary embodiment of a magnetic well tool, i.e. a magnetic junk basket, constructed in accordance with the principles of the present invention. ln FIG. 1 the magnetic tool 10 is shown removably secured to the lowermost section of pipe 12 of a pipe string provided with a circulation fluid bore 14. The tool 10 is further illustrated recovering magnetic or magnetizible objects indicated by the numeral 16 from a non-consolidated collection of non-magnetic debris, indicated by the numeral 18, such as comprising shale, etc.

Referring now simultaneously to FIGS. 2-4 it will be seen that the magnetic tool 10 comprises a unitary body member 20 such as machined, or otherwise formed from suitable metallic stock, such as stainless steel, for example, preferably of the type which can be heat treated to effect hardening thereof. As will become more apparent hereinafter the body member 20 need not necessarily be formed of a non-magnetic alloy. The upper portion of the body mem-ber 20 is provided with a coupling means designated by the numeral 22 for removably coupling the tool 10 to the lowermost sction of a pipe string 12. In the exemplary embodiment 10 illustrated the coupling means 22 comprises a threaded pin and box coupling means. However, it can be appreciated that the coupling means may comprise any suitable conventional means.

As seen best in FIG. 3 the body portion 20 beneath the coupling 22 is radially enlarged so as to provide for the reception of a cage means 24 within which are housed a plurality of permanent magnets 26 retained therein by a disk-like pole plate 28 secured to the cage 24, which will be understood is formed of a non-magnetic alloy, such as brass, for example, by means of weld bead 30. The brass cage 24 is received within a downwardly opening cylindrical recess as indicated at 32, which communicates with the lower end portion 21 of the body member 20. The cage 24 is pressed into the body 20` and fxedly secured therein by a weld bead 34 which is preferably continuous about the juncture of the cage 24 and lower portion 21 of the body member 20.

As seen best in FIG. 4 the magnetic means provided in the tool 10 comprises a plurality of permanent magnets 26 equidistantly spaced about a radius within complementary cylindrical recesses provided in the cage 24. The complementary recesses and the permanent magnets 26 are preferably sized so as to frictionally retain the magnets 26 therein. By way of example, the permanent magnets 26 each comprise a permanent magnet capable of exerting a lifting force of approximately 3,200 to 4,000 lbs., which it will be appreciated is generally sufficient to retrieve relatively large, heavy magnetic or magnetizible objects from a borehole or cased well.

Inasmuch as, and as illustrated in FIG. 1, lost objects, especially objects 16 within a well bore are very frequently partially or completely embedded within consolidated material, such as the material 18, the tool 10 is further provided with a circulation fluid passage means 40 comprising a centrally disposed and vertically extending bore 42 in the body member 20, generally of a lesser diameter than the bore 14 of the pipe 12. The bore 42 adjacent the upper end thereof is provided with a frusto-conically relieved portion 44 for effectively reducing the diameter of the bore 14 to that of the bore 42. It will be appreciated [ce 3,520,359v

that the aforementioned relationship of the relative diameter of the bore 14 and bore 42 is done so as to increase the velocity of circulation fluid passing downwardly through the bore 42.

A salient feature of the present invention resides in the constructional details of the manner in which the circulation fluid passage means 40 passes through the cage 24 to preclude fluid pressure, generated by circulation fluid passing downwardly through the bore 42, from acting upon the upper surface of the cage 24 whereby in the absence of a construction as dictated by the present invention, the cage 24 might be blown out of the body member 20 by the pressures generated by circulation fluid. It will thus be seen that the cage 24 is provided with a through-passage indicated by the numeral 46 concentric with the bore 42 but of a greater diameter than the bore 42. In addition, and as best seen in FIG. 3, the body member 20 includes a counterbore `48 concentric with the bore 46 and of the same diameter. The counterbore 48 is of suflicient depth, i.e. extends upwardly into the body 20 above the upper wall of the recess 32, a distance suflicient to accept a resilient seal member 50, such as an O-ring for example and the upper end of a circulation uid sleeve or magnetic cage blow-out prevention sleeve 52 having an enlarged peripheral lower flange S4. The sleeve 52 is press t upwardly through the cage 24 into sealing engagement with the seal member S thereby placing the bore 56 of the sleeve 52 in sealing communication with the bore 42. The sleeve 52 is secured in the assembled relationship best seen in FIG. 3, by a weld bead 58 about the juncture of the flange 54 and the cage 24.

From the foregoing it will be seen that the cage 24 is prevented from being blown-out, or washed out by circulation uid passing downwardly through the passage defined by the connecting bores 14, 42 and 56 whereby, as shown by the ow arrows in FIG. 3, the circulation is available for displacing unconsolidated material, such as the material 18, to permit the magnets 26, acting through the magnetic pole plate 28 to attract junk, such as the junk 16, whereby the junk 16 can be retrieved from the borehole by the withdrawal of the pipe string 12 from the borehole.

In addition, an exemplary embodiment of a magnetic tool constructed in accordance with the principles of the present invention, as exemplified by the tool 10, preferably includes a rotary guide shoe 60 coupled to the lower portion of the body member such as by the complementary threaded coupling means indicated by numeral 62 and lixedly secured to the body by welds 64, which as seen in FIG. 1, need not necessarily extend completely about the junction of the shoe 60 and the body 20. As seen best from a simultaneous consideration of FIGS. 1 and 3, the shoe 60 comprises a longitudinally extending annular ring including a downwardly spiralling lower edge portion 66 which delines a tooth member 68 for assisting circulation fluid in the unearthing of junk, such as junk 16 from unconsolidated material, such as the material 18. It will thus be appreciated that in the embodiment illustrated the shoe 60 is primarily adapted for maximum efliciency when the pipe string, and thus the tool 10, is rotated in a clockwise direction as seen in FIGS. 1, 3 and 4, which corresponds to a counter-clockwise rotation of the tool 10` as seen in FIG. 2. As will the body 20, the shoe 60 can, for example, be formed of heat hardened stainless steel.

Although a discussion of the utilization of the tool 10 has been inter-dispersed with the description of the structure thereof, the utilization of the tool 10 will be briefly summarized. Thus, and once again referring to FIG. 1, the tool 10 is coupled to the lowermost section of pipe 12 comprising a pipe string, when making up the string at the well head, and the string run in until the tool 10 bottoms, or should the junk to be retrieved be bridging the bore, until the tool comes to rest thereagainst. During the running in of the pipe it is to be understood it is generally preferable to maintain circulation of a conventional cirsuch junk, from the borehole by withdrawal of the pipe string from the borehole.

It will thus be seen that a magnetic tool construction in accordance with the present invention and provided with the magnetic pole at one end thereof as delined by the pole plate 28, magnetically and lixedly retains the magnets in the body of the tool 10 wherein washout prevent means insure that pressure generated by circulation fluid, generally necessary for the eliicient utilization of a magnetic retrieving tool, does not elect dislodgement of the aforementioned magnetic means.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modilications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. A magnetic well tool to be carried by a pipe string comprising an elongated body member provided with a downwardly opening recess, a first centrally disposed axially extending fluid passage means communicating said recess with a circulation fluid bore in a pipe string with which said magnetic tool is to be associated, a magnetic means fxedly secured in said recess and having a magnetic pole at the lower end portion thereof to attract and hold magnetic and magnetizible objects to be retrieved from a Well, said magnetic means including a second uid passage means in registry with said first fluid passage means for placing said iirst fluid passage .means in communication with the lower end portion of said magnetic means, and said second lluid passage means including sleeve means for precluding wash-out of said magnetic means from said body member by circulation fluid under pressure passing -downwardly through said first and second fluid passage means.

2. The combination of claim 1 wherein said magnetic means includes a non-magnetic cage substantially lilling said downwardly opening recess and having fixed therein a plurality of permanent magnet members generally equidistantly spaced about a radius, the ends of said permanent magnet members being contiguous with a magnet pole plate exposed at the lower end of said magnetic means.

3. The combination of claim 1 including a rotary shoe means lixedly secured to and downwardly depending from the lower end portion of said body member.

4. The combination of claim 1 wherein said iirst and second fluid passage means are in sealing communication at a point axially offset from the junction of the upper portion of said magnetic means with the contiguous axial surface of said body member defining the upper limit of said recess.

5. The combination of claim 2 wherein said sleeve means of the second Huid passage means has an upper end received in said body member in sealing engagement with said lirst fluid passage means, said sleeve means being ixedly secured in said magnetic means.

6. The combination of claim 5 wherein said means sealing juncture of said rst and second iiuid passage means comprises a resilient seal member.

7. A retrieving tool for well bores comprising an axially elongated body having a tubular lower end portion and a lluid conducting passage terminating at said tubular magnetic means secured to the body completely within the tubular end portion, conduit member extending through the magnetic means `for conducting fluid from the passage externally of the magnetic means and the body, said conduit member having opposite ends projecting axially from the magnetic means, retaining means securing one of the ends of the conduit means to the magnetic member, and means sealing the other of the ends of the conduit member to the body in axially spaced relation to the tubular end portion.

8. The combination of claim 7 wherein the magnetic means includes a non-magnetic cage completely"lling the tubular end portion of the body, a plurality of permanent magnets carried Within the cage in surrounding relation to the conduit means, and a pole plate secured to the cage adjacent said one of the ends of the conduit means retaining the magnets within the cage.

References Cited UNITED STATES PATENTS 2,734,767 2/1956 Donham. 2,830,663 4/1958 Kirby 166-99 X 2,833,353 5/1958 Walton et al. 166-99 X 2,891,621 6/1959 Walton et al. 166--99 X 3,019,845 2/1962 Mayall 175-328 3,378,089 4/1968 March 166-99 X DAVID H. BROWN, Primary Examiner U.S. Cl. X.R. 

